This application is based on Patent Application No. 10-374795(1998) filed Dec. 28, 1998 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a print head provided with a plurality of printing elements, and a printing apparatus for making printing by scanning the print head on a printing medium, and a method for driving the print head.
2. Description of the Prior Art
Heretofore, printing apparatus have been known which print an image by ejecting ink drops from a plurality of nozzles as printing elements to form dots on a printing medium.
In these printing apparatus, recently according to requirements for multicolor images, those types are becoming popular, one in which print heads for ejecting respective different color inks are arranged in a scanning direction of a carriage, and one in which a plurality of nozzle arrays for ejecting inks of different colors by each nozzle array.
Further, to form a high-resolution image, arrangement intervals of respective nozzles in the print head tend to become smaller. However, reduction of the nozzle arrangement intervals has a limitation. Then, for higher integration, a print head is provided in which a plurality of nozzle arrays are arranged in zigzags in alternation.
Still further, recently, a printing method may be used in which before or immediately after ejecting ink drops to the. printing medium, a treatment liquid for insolubilizing a color material of dyes in the ink is ejected to mix the ink with the treatment liquid on the printing medium. The treatment liquid is normally colorless and transparent, and respective liquid drops of the treatment liquid and printing liquid are ejected so that the treatment liquid and printing liquid are superposed on each other. The two liquids are mixed on the printing medium before the liquids are absorbed into the medium and fixed to the printing medium. Using this method, color development and water resistance of the ink are improved thereby preventing the ink from bleeding. In particular, this is effective for ordinary plain paper which is not coated with an ink accept layer. Further, when printing on a plain paper, there is a case of ink spreading along paper fibers, that is, so-called featheting, the use of the above treatment liquid is effective for preventing such feathering. An apparatus using a print head in which nozzle arrays for treatment liquid and nozzle arrays of inks are disposed side by side, or an apparatus in which respective print heads for the treatment liquid and inks are disposed, is provided.
In the print head provided with a plurality of nozzle arrays arranged as above, it is necessary that liquid drops of ink or treatment liquid ejected from respective nozzle arrays to the same pixels are accurately superposed or deposited at a predetermined position. However, accurate superposition of respective dots of ink of respective colors and treatment liquid, or accurate deposition of respective liquid drops at a predetermined position in the same pixel requires a very high precision in the positions of nozzle arrays, ejection speed, distance between papers, and it is relatively difficult to perform such adjustment in the production stage. Therefore, it has been conventionally known as a method (hereinafter referred to as xe2x80x9cuser head position adjustment methodxe2x80x9d) that a user of the printing apparatus previously makes it print a printing position adjustment pattern before performing printing and selects as ejection timing at which deposition positions coincide with each other, so that the printing position adjustment can be performed after the production stage.
Since a large amount of driving power is momentarily required to drive all of nozzles of the print head at the same time, a drive method in which nozzle arrays are divided into several blocks and drive is performed successively block by block (hereinafter referred to as xe2x80x9ctime division drivexe2x80x9d) is commonly used. In such time division drive, the blocks are driven to print respective vertical lines in association with movement of the carriage provided with the print head, and the vertical lines are deviated in the carriage moving direction by a predetermined amount for each block. Further, between respective scans, an end of a vertical line printed in a preceding scan is largely deviated from a connection which is an end of a vertical line printed in a succeeding scan. Due to the occurrence of such deviation, quality of formed image may sometimes be deteriorated. In order to cope with this problem, a method is proposed as described, for example, in Japanese Patent Application Laid-open No. 9-104113 (1997) in which nozzle arrays are disposed inclinedly by a predetermined angle, rather than vertically, and drive intervals between respective blocks are adjusted, thereby preventing especially connections from being deviated of between scans of vertical lines.
However, even with the drive interval adjustment method described in the above patent publication, merely the deviation of vertical line caused by block drive can be eliminated, but the overlap positions of inks or the like ejected from respective nozzle arrays cannot be adjusted. Further, since the above-described user head position adjustment method is 1-dot unit adjustment, a deviation of less than 1-dot cannot be adjusted.
Further, to perform the time division drive, it is necessary to send time division block signals to respective nozzle arrays, which has problems in that the number of head signals is increased, resulting in difficulty in routing of signal lines or an increase in cost. Therefore, a further increase of signal line for deposition position adjustment makes the problems even more intensified.
On the other hand, the print head of the structure in which two rows of nozzle array are arranged in zigzags and a supply port for supplying ink is provided at the center of the two rows of zigzag-arranged nozzle arrays is relatively low in strength, and structural changes tend to occur such that the two nozzle arrays are directed to the inside or, on the contrary, to the outside due to repeated ejections. Therefore, when printing is extended, a change tends to occur such that the deposition position of ejected ink drop is slightly deviated from an ideal position. However, for such a change in deposition position, the prior art printing apparatus has been impossible to make fine adjustment of deposition position of smaller than 1-dot unit.
It is therefore an object of the present invention to provide a print head and a printing apparatus and a print head driving method simply capable of forming print dots of ink and treatment liquid ejected from respective nozzle arrays at accurate positions.
A print head of the present invention is a print head provided with a plurality of printing element arrays each arranging a plurality of printing elements, said print head comprising:
a division drive circuit for dividing each of said plurality of printing element arrays into a plurality of drive blocks to drive a printing element for each of said plurality of drive blocks;
a driving timing input circuit for inputting a timing value indicating a timing of driving of the drive block; and
a delay value input circuit for inputting a delay value indicating an amount of shifting the timing, said delay value being set corresponding to each of said printing element arrays,
wherein said division drive circuit shifts a drive timing by drive blocks of drive time according to the delay value inputted by said delay value input circuit and performs driving of said plurality of drive blocks according to the timing value inputted by said driving timing input circuit.
A printing apparatus of the present invention is a printing apparatus provided with a plurality of printing element arrays each arranging a plurality of printing elements, said print head comprising:
a division drive means for dividing each of said plurality of printing element arrays into a plurality of drive blocks to drive a printing element for each of said plurality of drive blocks;
driving timing input means for inputting a timing value indicating a timing of driving of the drive block; and
delay value input means for inputting a delay value indicating an amount of shifting the timing, said delay value being set corresponding to each of said printing element arrays,
wherein said division drive means shifts a drive timing by drive blocks of drive time according to the delay value inputted by said delay value input means and performs driving of said plurality of drive blocks according to the timing value inputted by said driving timing input means.
A method for driving a print head of the present invention is a method for driving a print head provided with a plurality of printing element arrays each arranging a plurality of printing elements, said print head comprising:
a division drive step for dividing each of said plurality of printing element arrays into a plurality of drive blocks to drive a printing element for each of said plurality of drive blocks;
a driving timing input step for inputting a timing value indicating a timing of driving of the drive block; and
a delay value input step for inputting a delay value indicating an amount of shifting the timing, said delay value being set corresponding to each of said printing element arrays,
wherein said division drive step shifts a drive timing by drive blocks of drive time according to the delay value inputted by said delay value input step and performs driving of said plurality of drive blocks according to the timing value inputted by said driving timing input step.
According to the above configuration, since driving level can be set for each printing element and drive timing of each drive block be determined according to the driving level, adjustment of less than 1-dot of printing position is possible in a unit of each printing element array.
The above and other objects effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.